Why’s it so hard to predict the weather for Seattle?

We need good weather predictions so we know when we’ll have to dig our cars out. (Gilbert Arias/Seattle P-I)

Once the snow started coming down, the National Weather Service was pretty good with their predictions.

But last week as we teetered on the brink between rain and snow, predictions were a little more shaky and people were freaking out. The Associated Press even wrote a story mocking us for our “phobia” of the snow because everything started shutting down at even the threat of the white stuff.

So why’s it so hard to predict the weather around here?

Actually, it’s usually not, forecasters say. Spring and summer bring sun and a fair helping of rain. The fall and winter usually bring rain and more rain. But occasionally during the winter months, there’s the possibility of snow. That’s when it gets tricky.

“In the winter we’re sometimes right on the edge of it being cold enough to snow in the winter,” says Chris Burke, a National Weather Service meteorologist. “A degree or two could make the difference between snow or rain.”

Unlike the Midwest – where there’s a guarantee of snow in December or January – in Seattle there’s simply no way to know for sure what’s going to happen when we’re on the edge between snow and rain. Meteorologists give their best guesses, but even with improving technology they’re still guesses.

“What we worry about is these smaller, short-term events that are inherently less predictable,” said Dale R. Durran, a professor in the atmospheric studies department at the University of Washington. “Thunderstorms, for instance, have the ability to evolve and change in just a few hours.”

When we get on the edge of weird weather in Seattle, things are much tougher to predict than elsewhere. Meteorologists say the trickiness will remain for the foreseeable future. Here’s a helpful story from the P-I’s Tom Paulson that talks about some of this trickiness as well as the challenges of conveying weather-related information to the public.